Balance studies were conducted with preadolescent girls maintained under controlled conditions. The children were fed a diet containing 23 g. protein and 5.5 mg. zinc. Diets of two groups of children were improved with essential amino acids to achieve a chemical score of 80 relative to egg; the other diets were made isonitrogenous with ammonium citrate. Zinc was brought to 10.5 mg in two diets giving a 2 x 2 factorial design. Neither amino acids nor additional zinc improved nitrogen retention by the growing children. BIBLIOGRAPHIC REFERENCES: Korslund, M.K., E.Y. Leung, C.R. Meiners, M.G. Crews, J. Taper, R.P. Abernathy and S.J. Richey. 1976. The effects of sweat nitrogen losses in evaluating protein utilization by preadolescent children. Am. J. Clin. Nutr. (accepted for publication). Harrison, M.E., Coleen Walls, Mary K. Korslund, and S.J. Ritchey. 1976. An estimation of mineral losses through arm sweat of preadolescent children. Am. J. Clin. Nutr. (submitted and revised).